Cervical plate

Abstract

Screw back out prevention devices to inhibit screws from reverse threading or backing out are provided. The devices include first bonding materials on either a bushing in a bore of a plate or directly on the bore and second bonding materials on the screw head. The bonding materials for a bond that inhibits back out or reverse threading of the screw.

We claim: 
     
       1. A back out prevention device in a cervical plate, the cervical plate comprising at least one through hole, the prevention device comprising:
 a bushing residing in the through hole; 
 a screw; and 
 at least one first bonding material, wherein 
 the bushing has an inner sidewall containing a first groove therein, wherein the first groove has at least first and second portions that reside on opposing sides of the inner sidewall of the bushing and the at least one first bonding material residing in the first groove, wherein 
 the screw comprises a screw head and a shank, wherein 
 the screw head has an outer sidewall containing a second groove therein, wherein the second groove has at least first and second portions that reside on opposing sides of the outer sidewall and at least one second bonding material residing in the second groove, and the first and second portions of the first groove and the first and second portions of the second groove are configured to align coaxially with one another and form a space extending therebetween when the bushing and the screw head are configured in attachment with one another, such that 
 when the screw is threaded into a vertebral body, the at least one first bonding material in the first groove of the inner sidewall aligns with the at least one second bonding material in the second groove of the outer sidewall to fill the space extending therebetween and to form a bond that inhibits the screw from backing out. 
 
     
     
       2. The screw back out prevention device according to  claim 1 , wherein the at least one first bonding material and the at least one second bonding material are self-bonding materials. 
     
     
       3. The screw back out prevention device according to  claim 2 , wherein the self bonding material is coated on the inner sidewall and the outer sidewall. 
     
     
       4. The screw back out prevention device according to  claim 1 , wherein the at least one first bonding material and the at least one second bonding material are at least one of a thermally activated bonding material, pressure activated bonding material, an electrically activated bonding material, and a radiation activated bonding material. 
     
     
       5. The screw back out prevention device according to  claim 1 , wherein the at least one first bonding material and the at least one second bonding material are different materials. 
     
     
       6. The screw back out prevention device according to  claim 1 , wherein the at least one first bonding material and the at least one second bonding material are at least one of an epoxy, an acrylics, a resin, a silicone, an adhesive, a glue, and a tape. 
     
     
       7. A back out prevention device in a cervical plate, the cervical plate comprising at least one through hole, the prevention device comprising:
 a bushing residing in the through hole, the bushing comprising a bore; 
 a screw; 
 the bushing has an inner sidewall containing a first groove that has opposing portions that are coaxially aligned on opposite sides of the bushing and a first bonding material residing in the first groove; 
 the screw comprises a screw head containing a second groove that has opposing portions that are coaxially aligned on opposite sides of the screw head and a shank and a second bonding material residing in the second groove, and the opposing portions of the first groove are coaxially aligned with the opposing portions of the second groove when the bushing and the screw head are configured in attachment with one another; such that 
 when the screw is threaded into a vertebral body, the first bonding material in the first groove substantially aligns with the second bonding material in the second groove of the screw head forming a bond that inhibits the screw from backing out.